The area made by an arc and a chord is called the Segment of the Circle.
Minor Segment
The area made by chord AB and arc X is the minor segment. The area of the minor segment can be calculated by
Area of Minor Segment = Area of Minor Sector – Area of ∆ABO
Major Segment
The other part of the circle except for the area of the minor segment is called a Major Segment.
Area of Major Segment Area of Minor Segment